Renal cell carcinoma (RCC) accounts for 3% of all adult malignancies and there are approximately 32,000 new cases diagnosed each year in the United States. RCC is resistant to virtually all conventional modes of treatment, such as radiotherapy and chemotherapy, reinforcing the urgent need for new therapies. RCC is a clinicopathologically heterogeneous disease, traditionally subdivided into clear cell, granular cell, papillary, chromophobe, spindle cell, cystic, and collecting duct carcinoma subtypes based on morphological features according to the WHO International Histological Classification of Kidney Tumors (Mostfi, 1998). Clear cell RCC is the most common adult renal neoplasm, representing 70% of all renal neoplasms, and is thought to originate in the proximal tubules. Clear cell RCC is mostly sporadic, unilateral, and unifocal. The main genetic alterations of clear cell RCC have been identified to be chromosome 3 alterations and Von Hippel-Landau (VHL) gene mutations (Walsh, 2003). pVHL is part of a novel multiprotein ubiquitin ligase complex, termed VBC (VHL/Elongin B/Elongin C), that recruits important cellular proteins for rapid degradation by the ubiquitin-proteasome proteolysis system. Among the cellular proteins that bind to VHL and are normally degraded under normoxic conditions is hypoxia-inducible transcription factor (HIF1). HIF1 is considered to be a master regulator gene that integrates pathways regulating physiological responses to acute and chronic hypoxia. HIF1 controls the expression of several dozen target genes, including those involved in energy metabolism (glucose transporters, glycolytic enzymes), angiogenesis [vascular endothelial growth factor (VEGF) and VEGFR-1], and surface transmembrane carbonic anhydrases (CAs) (Hanahan, 1996; Ivanov, 1998; Maxwell, 1999; Ohh, 1999; Semenza, 2000). In VHL-defective tumors, curiously enough, the two fundamental stages of tumor development occur either simultaneously or in reverse, first triggering the hypoxia-cellular response, followed by proliferation of transformed cells, consistent with the angiogenic phenotype of tumors seen in the VHL syndrome (Ivanov, 2001). RCC is one of the few tumors where spontaneous regression of metastatic disease has been documented after tumor nephrectomy, treatment with placebo in phase III trials or after inflammatory or infectious events (Bleumer, 2003; Michael, 2003). These observations have provided strong evidence of the importance of the immune system in the control of this cancer. Therefore, much attention has been focused on immunotherapeutic modalities for the treatment of RCC.